1. Field of the Invention
The present invention relates to an apparatus and method for manufacturing a substrate, and more particularly, to an exposure apparatus and method for transferring a pattern formed in a mask onto a substrate, and a mask stage used for the exposure apparatus and method.
2. Description of the Related Art
Generally, a plurality of processes, such as an ion implantation process, a deposition process, a diffusion process, a photolithography process, and an etching process are required to manufacture a semiconductor device. The photolithography process is used for forming a desired pattern on a wafer. The photolithography process typically includes a coating process for coating a photoresist on a wafer, an exposure process for illuminating light to transfer a pattern formed in a mask onto the photoresist, and a developing process for removing the photoresist from a predetermined region on the wafer after the exposure process.
An apparatus for performing the exposure process may include: a mask stage on which a mask is placed, a light source for illuminating light onto the mask, a wafer stage on which a wafer is placed, and a projection lens located between the mask stage and the wafer stage to project light that has passed through the mask onto the wafer. A plurality of masks having different patterns are used when the exposure process is performed on one of several wafers belonging to different groups, wafers belonging to the same group, or a single wafer. A generally used mask stage has a limited structure where the mask stage mounts only a single mask thereon. Therefore, when a mask in which a different pattern is formed is to be used during a process, a mask that has already been mounted on the mask stage should be replaced. To replace a mask, the mask that has been used is unloaded from the mask stage, and a new mask is drawn out from a mask storage place such as a library and a SMIF pod, and then a position of the drawn-out new mask is aligned and loaded onto the mask stage. Movement of a mask is performed slowly so that the mask may be mounted on the mask stage with its position aligned. Therefore, it takes a relatively long time to replace the mask.